<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
	<input type="button" value="">
	<script>
		var btn = document.querySelector('input');
		document.addEventListener('click', text, false)
		function text (ev) {
			console.log(this+'-' + ev.currentTarget + '-' + ev.target)
			//[object HTMLDocument]-[object HTMLDocument]-[object HTMLInputElement]
		}
	</script>
</body>
</html>